In-the-ear or ITE hearing aids have been manufactured for some time. Such aids include full concha aids, low profile full concha aids, half concha aids, canal aids, and semi-canal aids. In all cases there exists a need to build smaller hearing aids which will fit more ears. There is also a need to build such hearing aids with better performance and more features.
Traditional custom ITE hearing aids have been constructed by creating a shell which anatomically duplicates the relevant parts of the user's ear canal and concha. A receiver is placed in this shell, and then the open end of the shell is closed with a faceplate subassembly. The faceplate subassembly consists of an arrangement of individual components, typically an amplifier, microphone, volume control, battery compartment and potentiometers for adjusting the hearing aid performance to the user's individual needs. Adjustment or repair of the internal parts requires the faceplate to be cut away from the shell. This is an awkward procedure, and after repair or adjustment, subsequent buffing or polishing is needed to restore the hearing aid to an acceptable cosmetic appearance.
These difficulties have motivated the construction of modular hearing aids in which an electroacoustic module (consisting of a receiver, which is simply a miniature loudspeaker, a microphone, an amplifier, a battery compartment, a volume control and other optional controls) is mated into a faceplate with a matching opening. The module can be inserted into and removed from a faceplate-shell subassembly to make the building and repair of the hearing aid more efficient. However a detrimental consequence of modularity has been an increase in the size of finished hearing aid.
In all existing modular ITE hearing aids, the module contains a battery compartment with a battery compartment lid attached to the module. The size of the lid is determined by the dimensions of the battery and the space required to provide a hinge to fasten the battery lid to the modular insert. The hinged lid is opened frequently to exchange batteries, thus exerting wear and tear on the module. In current modular hearing aids, the module must fit snugly into the faceplate and must be securely attached to the faceplate by a suitable snap or fastening detail. Usually latches or the like are used to provide a secure fastening. Both the hinge and the fastening detail add considerably to the size of the module and thus to the size of the finished aid. As a result, modular ITE hearing aids which are presently available are not suitable for more than 40 to 50 percent of all ears which could be candidates for such hearing aids.